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Topic: Lm386 mic preamp? (Read 10476 times)

Someone in a thread I was looking at said the built a clean mic preamp with a lm386. Can you cascade these op amps in anyway? I want clean 1/4" in/out mic pre and since I bought a few Lm386 for a smash drive I figured icould find out

i guess my other question would be. if not the lm386. how can i use a dual op amp to create a quiet yet loudly effective mic preamp?

what would be quieter making a two channel preamp with each half? or using both with a small boost hooked up to a dual gang pot ? like would that help keep the noise from entering the signal and amplify the signal quite a bit? i want to use this as a mic preamp and a preamp for my acoustic electric

http://sound.westhost.com/project66.htm Will you like the 386 is where I'd try to finish the questions, beginning with a 386 configured on BB or board, using a datasheet circuit, or other. The power supply...near maxV should give a strong boost, and minimize the ''386 sound''.

No noise is specified. But the 50K input and particularly the internal currents are a lot like the preamps we used when 1/4" was still a common mike input, on tape-decks and non-Pro mixers.

I bet a good '386 has input noise voltage across the audio band near 1uV-2uV, a hair lower than most all-purpose opamps.

> need between 1000x and 10,000x Gain

A low-Z ribbon on a harpsichord into a might need 80dB gain. Using dynamics on live performers (often not loud) I was always fine with 2mV-5mV input sensitivity for peak level. Most "line" inputs are fine with 500mV-1,000mV. Gain of 200 (46dB) is often ample.

An awful lot of good music was recorded with preamps not as snazzy as the '386.

It IS about 1,000 times the "grunt" you need to swing 10K line inputs. But with '386 prices what they are, it isn't like it costs too much.

Come on PRR , you know your electronics and you know very well that the Lm386 is a Noisy piece of Crap chip especially for a Mic preamp , compare 0.2% at 1khz THD for the LM386 and 0.004% THD for the Ina217,... And while you might need 10000x gain for a Ribbon mic , you will still need at least 50-60db for many dynamics or 2000x gain .....

Are you just playing the devils advocate ?? it doesn"t suit you especially when you know Im right .... You can do way better even with a Lowly TL072 ....

And snazzy and the LM386 should never be used in the same sentence .....

It doesn"t matter which , Low Noise and low THD are needed for a good mic preamp , pluss the Lm386 datasheet doesn"t even have a spec for Noise (not a good sign) but its THD goes up to 10% when at max output .... It just simply isn"t suitable for a Mic pre unless you just want a Noise maker or a Toy, which is cool if that is what you want buy it wouldn"t be anything that you would use in a studio .....

For the Same price of a LM386 you can get a TL072 or a NE5532 which could be made into a useable mic preamp .....

It doesn"t matter which , Low Noise and low THD are needed for a good mic preamp , pluss the Lm386 datasheet doesn"t even have a spec for Noise (not a good sign) but its THD goes up to 10% when at max output .... It just simply isn"t suitable for a Mic pre unless you just want a Noise maker or a Toy, which is cool if that is what you want buy it wouldn"t be anything that you would use in a studio .....

For the Same price of a LM386 you can get a TL072 or a NE5532 which could be made into a useable mic preamp .....

The dude is talking about a 1/4" mic input - obviously not balanced. I am just going to venture a guess here and say this obviously isn't for a super hi-fi studio situation, unless you know of any professional studios that use unbalanced 1/4" mics.

I don't want to speak for the guy, but he may not need the cleanest most pristine thing ever for this project, but maybe just something that will get the job done simply and quickly... for that 386 excels.

Seriously plenty of studios still do. Especially with vintage mics. It's balanced up til the last 6 inches where the adapter is. Ad I kinda wanted a mic pre that gives that old school light saturation kinda of sound. I have nice mic preamps tht I have bought including a U.I.Just wanted to experiment for cheap, if not it would make a great bass preamp.

I use those kinds of mics in my studio, but generally any professional studio is wired for balanced xlr throughout and the use of a 1/4" mic is for effect/special occasions. High fidelity preamps are generally not designed with 1/4" unbalanced in mind.

The point stands. If you are using 1/4" mics, it isn't for super pristine high fidelity sound.

If you want to experiment for cheap, then do it, 386 is just the thing!